Grass mower



R. HESS GRASS MowER Filed April 26. 1926 Feb. 12, 1929.

III it' e d h, l., .n e d .n b

Patented Feb. 12, 1929.

RICHARD nnss, or Bnnnnnnnswannn, einen. Piane, GERMANY.

GRASS MOWER.

Application filed April 26, 1926, Serial No. 104,699, and in Germany May l, 1925.

'This invention relates to a grass mower the knives of which, cutting like scissorsl` have arc-shaped inner ends and are operated by knife hars. ln machines of this type of known construction the knives are pivotally connected for instance to a finger bar, the inner arcshaped ends of the knives being sunk into a plate so that this plate is flush with the knives. The object of this arrangement, to

lo prevent clogging or jamming of the cutting mechanism by the material which is cut or by other foreign bodies, is not attained for the reason that the fingers which operate the knives form too short lever arms.'

According to the invention shank-like elements are arranged alternately underneath and ahove the knives, the ends of said elements which are fixed on the knives having arcshapcd side edges. The center of these arcslnped side edges coincides with the pivot point of the knives and the diameter of the enlarged. parts of the elements is so great, that the edges of the. arc-shaped ends of the cutting knives abut the arc-shaped side-edges of the adjacent elements in such a manner that, in any position of the cutting knives, they are in mutual Contact with the adjacent elements. The lower knives are moved from the upper knife ybar and the upper 'knives from the lower knife bar. By the shank-like elements not only a perfect covering of the knife mechanism towards the outer side is en sured hut also a uniform cutting even when more power is required.

An embodiment of the invention is shown, by way of example, in the accompanying drawing in which Fig. l shows in plan view the knife-mecha nism.

Fig. 2 knives. f Fig. 3 is a side elevation partly in section of the knife-mechanism.

Fig. 4 shows on larger scale in cross section the head portion of the knife heam andl in elevation the extensions of the knives.

Fig. 5 shows in top plan view a portion of the connecting rod and the claws connecting the double lever to the connecting rod.

Fig. 6 is a side elevation of Fig. 5.

On the cutting knives a, a arms Z) are hxcd which form extensions of thel knives. The front ends of the arms are arc-shaped, the center of these arc-shaped front ends being shows on larger scale some of the the pivot point for the knives and the parts o of the extensions which rest upon the lorries f;

knives form arcs concentric to the knife-ends.

The breadth of the parts o of the extensions corresponds tothe interval between two adj acent knives. The knives are arranged so that the end of theA one knife rests permanently upon or under the ends ofthe adjacent knives and bears permanently against the circular part of the adjacent arm b, i. e. is permanently in touch with the same. The knives a, a are fixed by means of screws g screwed into the knifebeam 7L, said screws serving at the saine time as pivot pins for the knives. The extensions of the top knives a, are always under the knives and engage with cut out portions d. in the lower knife har e, the arms Z) of the bottom knives a engaging with cut out portions Z of the upper knife-bar f. If the cuttingknives a, a are pivoted around g owing to the shifting of the knife-bars e, j, the cutting knives are oscillated and the side edges remain permanently in contact with the side edges om the arc-shaped parts Z9 of the extensions Z). A bar r covers the knifemechanism so that thek same is well protected.

rlChe knife hars c, f are mounted so that they can easily shift upon the knife-beam 7i. The shifting is effected from a double lever e' throughthe intermediary of rods 7c. rJhe movement of the lever z' is controlled by a crank-disk Z mounted upon the knife-beam and connected by a connecting rod m to the lever'z' which oscillates around n. The knifemechanism may be manufactured` and supplied independently of the other elements and it can he inserted into any existing grass mower.

The end o of lever z is preferably ballshaped and this lever is connected with the connecting rod m by two concave claws 0 adjustably mounted on the connecting rod m, the concavity of said claws corresponding to the ball-shaped end 0 of the lever z' (Figs. 5 and 6) I claim A grass mowor,comprising in combination,y two superposed sets of oscillatahle knives said knives having arc-shaped inner ends, an upper knife bar for operating the knives of the lower set, a lower knife har for operating the knives of the upper set, shank like elements one for each knife and fixed alterately on and under the knives, an enlarged part at that end of each elenleni which is pivotally lixedV on the knife7 said enlarged part having aroshaped side edges and Jthe @entre of said ares coinciding` with the pivot point of the corre- 'spending` knife the diameter of the enlarged part being sue-h that the knives are permanently in Contact with the sides of the en lzu'ged Darts of the two adjacent elements and Suid elements being of such thickness that they Will freely oscillante With regard to each 10 other so that seid elements do not strike against euch other.

In testimony whereof I my signature.

RICHARD HESS. 

